Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2013
Publication Date: 7/31/2013
Publication URL: http://handle.nal.usda.gov/10113/58809
Citation: Kiszonas, A.M., Fuerst, E.P., Morris, C.F. 2013. Wheat arabinoxylan structure provides insight into function. Cereal Chemistry. 90:387-395. Interpretive Summary: Arabinoxylans have a unique structure, which contributes to their important function in plant physiology and end-use quality. The complex and heterogeneous structure leads to two very diverse fractions based on water extractability. These two fractions, WEAX and WUAX, differ in their physical properties with respect to arabinose substitution and molecular weight. This results in varied influence on end-use quality. The genetic and environmental influences on arabinoxylan molecules does not conclusively suggest complete genetic or environmental control over the abundance or structure of the molecules. Because of these varied results across many studies, and the highly variable nature of arabinoxylan influence over end-use quality, there is a wealth of research that may still be undertaken to further understand the complex nature of arabinoxylan molecules.
Technical Abstract: Recent attention to dietary fiber in wheat (Triticum aestivum L.) has invigorated research in the non-starch carbohydrate arabinoxylan. Arabinoxylan (AX) molecules are comprised of a linear xylose backbone with arabinose substitutions along the backbone. These arabinose substituents can also carry a ferulic acid moiety. Arabinoxylan molecules can be fractionated into two categories based on structural and conformational properties: water-extractable (WEAX) and water-unextractable (WUAX) molecules. The ferulic acid moieties also allow for oxidative cross-linking between AX molecules, or the tyrosine residues of proteins. The content of total AX and WEAX molecules is primarily influenced by genetic differences; however, there is also evidence of environmental influence on content. There are several useful methods for quantifying AX molecules, providing varying levels of structural information as well as accuracy and precision. The high water-absorption capacity of AX molecules results in a strong influence of AX on end-use quality. Whereas WEAX molecules, in particular, tend to be detrimental for the quality of soft wheat products, WEAX molecules are beneficial to the quality of hard wheat products. The role of WUAX molecules in soft wheat products is as yet unclear; however, WUAX molecules tend to have a detrimental influence on hard wheat quality products. Further investigation is necessary to obtain a more complete understanding of how the arabinose substitution levels and patterns affect end-use quality, and how the genetic basis of these traits can be resolved and manipulated for optimum end-use quality.